On June 22, 2022 Propanc Biopharma, Inc. (OTCQB: PPCB) ("Propanc" or the "Company"), a biopharmaceutical company developing novel cancer treatments for patients suffering from recurring and metastatic cancer, reported that the results from a small trial of just 18 rectal cancer patients in complete remission using an immunotherapy called dostarlimab are "impressive," whilst acknowledging there’s more work to be done (Press release, Propanc, JUN 22, 2022, View Source [SID1234616184]). Chief Scientific Officer and Co-Founder, Dr Julian Kenyon MD, MB, ChB, believes that the field’s biggest challenge remains that immunotherapies work inconsistently across cancers. Oncologists estimate a response rate of 20% across cancer types, according to the Wall Street Journal ("WSJ"). The drugs can wipe out cancers from some people, but fail to work for others. It is also uncertain whether the cancer may eventually return once a patient is in remission, even after a prolonged period of time.
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Immunotherapies like dostarlimab, known as a checkpoint inhibitor, seek to inhibit key regulators of the immune system that when stimulated, reduces the body’s immune response to fight cancer. Given that immunotherapies target specific gene sequences, it often means they can encounter resistance, due to mutations that occur and genetic variation even within the primary tumor of a patient. As a result, Dr Cercek, from Memorial Sloan Kettering, who conducted the study for dostarlimab, estimates only 10% of rectal cancer patients and about 4% of all cancers will respond to treatment, according to the WSJ.
"For many cancers, multiple factors can drive growth, making it hard to effectively match one biomarker, or a particular gene sequence, to a single drug. On the other hand, a therapeutic approach like our lead product candidate, PRP, which alters the characteristics of the cancer cell, by enforcing it to express proteins it normally wouldn’t, means the treatment is less likely to encounter resistance through mutations, which is what we have observed in the lab as well as in clinical practice," said Dr Julian Kenyon.
In addition to specifically selecting the 18 rectal cancer patients according to their genetic biomarker, the trial included patients that were pre-metastatic, where tumors were locally advanced in one area, but not spread to other organs. This means patients identified with metastatic cancer were excluded from the trial. Therefore, the treatment and prevention of metastatic cancer, the main cause of patient death for sufferers, still remains the unsolved, final frontier. Cancer stem cells, which are the cells responsible for spreading to other parts of the body, remains a key focus for Dr Kenyon.
Dr Kenyon said, "PRP is a proenzyme treatment that targets and eradicates cancer stem cells by altering multiple pathways of a cancerous cell rather than a single genetic sequence. We’ve observed that once they are treated with PRP, the effects are irreversible and are more easily recognizable by the immune system, therefore potentially improving the response rates of standard approaches like immunotherapy, to overcome advanced cancers. We look forward to testing the utility of PRP with these approaches as we further advance into the clinic."
PRP is a mixture of two proenzymes, trypsinogen and chymotrypsinogen from bovine pancreas administered by intravenous injection. A synergistic ratio of 1:6 inhibits growth of most tumor cells. Examples include kidney, ovarian, breast, brain, prostate, colorectal, lung, liver, uterine and skin cancers.